The present invention relates to noise reduction by compression and expansion of original signals, and in particular to a noise reduction circuit which mitigates the problem associated with a phenomenon known as "breathing" caused by the modulation of a gain control signal on the noise introduced by a transmission or recording medium.
Noise reduction techniques have been extensively employed in recording to minimize the effect of noise generated in the recording material or introduced by a transmission medium by effecting the compression of the signal prior to recording or transmission and effecting the expansion of the reproduced or received signal. However, conventional noise reduction systems for multi-channel stereophony are still affected by the breathing phenomenon which is particularly acute when there is a phase difference of 180 degrees between the channels.